It has become common practice to use disposable diapers with infants and incontinent children and adults. Disposable diapers generally have a rectangular or hour-glass shape and comprise an absorbant back material sandwiched between an outer flexible polyethylene backsheet and an inner polypropylene or polyester nonwoven frontsheet. The outer backsheet typically, but not necessarily, is moisture vapor-pervious, but water-impervious to prevent voided liquid absorbed into the absorbant back material from striking through the diaper and soiling the person's adjacent clothing or bedding. The inner front sheet on the other hand is water-pervious to permit the voided liquid to pass therethrough into the absorbant back material to maintain the person in a dry, comfortable state.
It is also well known and common practice in manufacturing disposable diapers to rely upon pressure-sensitive adhesive tape-tab fasteners as means for fastening the diapers about people. The safety advantages and convenience of tape-tab fasteners, rather than pins, is self evident. Notwithstanding their popularity, to date there are several shortcomings associated with the use of tape-tab fasteners. One major shortcoming lies in the loss of tape adhesion between the tape-tab fasteners and backsheets following their original attachments, especially when the backsheets are formed with a polyethylene polymer. Such loss in tape adhesion during normal use discourages users from wanting to use disposable diapers especially in view of costs associated with their use.
Another major shortcoming lies in the tearing of backsheets when the tape-tab fastener, which have high tacky surfaces to prevent tape adhesion loss between the fasteners and the backsheets, are intentionally detached therefrom following their initial attachments, especially when the backsheets are formed with a polyethylene polymer. This tearing phenomenon discourages users from detaching the tape-tab fasteners from the backsheets once the diapers are assembled.
Yet another major shortcoming lies in the stiffness of backsheets formed with high density polyethylene and polypropylene polymers. It is well known to those versed in this field that low stiffness or softness is especially desirable for imparting satisfactory drape qualities to the backsheets. However, backsheets formed with high density polyethylene and polypropylene polymers, as indicated earlier herein, are typically very stiff and brittle and therefore have been known to split or crack on their own during normal use when the disposable diapers are assembled about people. On the other hand, backsheets formed with polyethylene polymers, while softer or less stiffer than backsheets formed with high density polyethylene and polypropylene polymers, are known to tear when the tape-tab fasteners are intentionally detached therefrom for repositioning.
These shortcomings become immediately apparent when users, such as parents, attempt to use disposable diapers formed with these backsheets, and more particularly attempt to unfasten the tape-tab fasteners to routinely inspect for soiled diapers and then refasten same following inspection. Consequently, these inefficiencies in the backsheets have resulted in unsoiled, disposable diapers being commonly discarded during normal use and following routine inspection, especially during the toilet-training ritual. The lack of reuseability of disposable diapers due to the shortcomings associated with the backsheets available heretofore is not only inconvenient but is also expensive in view of rising costs associated with disposable diapers.
In an attempt to resolve these problems with conventional polyethylene and polypropylene back-sheets, the disposable diaper manufacturers have resorted to gluing strips of heavy gauge, typically 2-3 mils, polypropylene onto conventional low density polyethylene backsheets to form heterologous backsheets having distinct, stiff landing or positioning zones for receiving the tape-tab fasteners thereon. Unfortunately, this is a costly procedure, since it requires the use of adhesives to affix the polypropylene strips thereto and additional processing steps to formulate these heterologous backsheets.
Consequently, there is a present need for backsheets for use with absorbant articles, such as disposable diapers, which are soft and pliable, but which do not tear upon detaching the tape-tab fasteners from such backsheets for repositioning or lose substantial tape adhesion therebetween during normal use following original attachment, and which do not require additional materials and non-extruding processing steps to form same.